In his new weekly column, our consumer expert makes sure you don't lose out
when part-exchanging your car.

The scrappage scheme of 2009-10, in which a dealer took your old car and gave you £2,000 towards its replacement, had many benefits for buyers – not least because it made selling an outmoded model easier than it ever had been. Shame it's not still running, because trading in your car can leave you badly out of pocket if you get it wrong.

For a start, consider the price you'll get for your old car. The dealer has an instant advantage because he will have a Cap or Glass's Guide to hand. This provides the price to pay (the trade price) for and then sell (the retail price) nearly every car in a combination of virtually every age, specification, mileage and condition.

If you can't get hold of a copy of Cap or Glass's Guide, both offer free valuation services on their websites. Alternatively, visit a variety of car sales websites to see what similar cars to yours (including trim and mileage) are selling for. Armed with this information, you'll know how much the dealer's initial offer is below the trade price.

However, as far as the dealer is concerned, you're not just negotiating on the car you're selling. He will be putting two figures in your head: your old car's value and what you're paying for the new model.

If the car you're buying is on finance, any dealer worth their shiny suit will also add the size of the deposit and the monthly repayments to the equation. So you'll be drinking their complimentary coffee trying to separate four inseparable figures and not stitch yourself up in the process. It's an equation even Carol Vorderman would struggle with. Trading in a car in might be billed as easy, but in reality it's far from it.

I think the preferable alternative is selling privately or to a used-car dealer. Never accept the first price a dealer gives you and always remember you'll get more for selling the car privately. It'll involve a degree of hassle and possibly talking to time-wasters, but you'll be able to pocket the difference between trade and retail prices. More importantly, it won't complicate negotiations over the price of your new wheels.

HOW TO BEHAVE IN A CAR SHOWROOM

When you're buying a car, whether it's new or used, you'll probably be in the hands of someone who does it every working day of their lives. Practice, in this case, might not make perfect, but it does make car dealers a damn sight better at getting what they want than their customers.

Part of this is because they know their product very well. Your research will have narrowed down a shortlist of cars from different manufacturers and you should know exactly which model you want, what price you're willing to pay and how you're going to pay for it. You may even have a list of prices from the internet to which dealers can match their price.

This will help in two ways. First, buying a car is driven by emotion. The more facts at your disposal the more rational the decision becomes. And you'll be able to tell when you're being spun a line.

If you're being ignored, introduce yourself politely to the receptionist, make it clear why you're there and you should be seen fairly promptly. If you continue to be ignored, explain that you have an appointment with the rival dealer down the road and if that doesn't incite immediate action, walk out.

That's the key point to remember throughout the car-buying process. You are ultimately in charge. If you don't like the way the salesperson treated you, or the way they dismissed your suggestion of a discount, if you don't like the colour and trim options they're offering, if you don't want to wait six months for delivery, or think you can buy the car cheaper over the internet, leave.

RAKING IT IN WITH A RUN-OUT?

Buying a car that's about to be replaced or updated can either be a big mistake or save you big money. It's a mistake if you inadvertently buy a run-out model at or near full price because it should be a god-given opportunity to negotiate a big discount. New cars at the end of their particular model's life depreciate faster than previously because second-hand buyers can wait for the new, probably better, version. You need to account for that in the price you pay. Or wait for the replacement.

But if haggling is a skill you can only admire in others, buying a run-out model of cars that dealers are struggling to shift can do the job. For example, Mitsubishi is offering £4,000 off its current Outlander, because it's being replaced in April.

DEAL OF THE WEEK

The Volvo XC90 is showing its age so even Volvo dealers are giving big discounts to shift them. I found £13,540 off a £47,530 ex-demo XC90 R Design at www.motorparks.co.uk/volvo-ex-demo. The company also has £9,020 off a £44,020 XC60 AWD R Design.

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